Post validator for bill acceptor

ABSTRACT

A post validator arrangement for a bill acceptor of a type known in the prior art utilizing a combination of photoelectric and magnetic checks of an item of currency passing therethrough in which the item is required to pass a secondary magnetic test at a location beyond an improved one-way mechanical gate positioned at the outlet of the bill acceptor.

United States Patent 1 1 1111 3,715,031 Okkonen 1 Feb. 6, 1973 [54] POST VALIDATOR FOR BILL 3,275,138 9/1966 Cahill ..209/DIG. 2 ACCEPTOR 3,543,904 12/1970 Constable ..194/4 c [75] Inventor: Oliver G. Okkonen, Comstock Park,

Mich' Primary Examiner-Allen N. Knowles [73] Assignee: Rowe International, Inc., Whippany, Attorney-Shem & OConnor [22] Filed: April 14, 1971 [57] ABSTRACT [21] Appl' 133347 A post validator arrangement for a bill acceptor of a type known in the prior art utilizing a combination of [52 US. Cl ..209/75, 209/1 1 1.8, 209/DIG. 2 Photoelectric and magnetic checks of item Of [51] Int Cl l U 807C 3/16 rency passing therethrough in which the item is [58] Field of 1 H 8 required to pass a secondary magnetic test at a location beyond an improved one-way mechanical gate 194/4 4 4 4 4 4 232/4 62 positioned at the outlet of the bill acceptor.

[56] References Cited 17 Claims, 3 Drawing Figures UNITED STATES PATENTS 3,265,205 3/1966 Chumley ..209/DlG. 2

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POST VALIDATOR FOR BILLACCEPTOR BACKGROUND OF THE INVENTION With the increasing useof merchandising machines and under the press of inflation, there have been developed in the prior art devices which make change in response to the insertionof adollar bill therein; Such devices also are incorporated in machines to pennit articles or services to be purchased for currency rather than requiring the customer to use coins. One such device is shown. and described in Hooker U.S. Pat. No. 3,485,358. That device puts out asignal in response to passage therethrough ofa valid dollar bill. It will readily be appreciated that great caremust be taken in such a device to ensure that change is made or a credit signal is given only in response to passage of a valid bill through thedevice andthat the possibilities of cheating the acceptor must be kept toaminimum if not entirely eliminated. In order to test a bill in the device shown in the patent, it must pass both photoelectric and magnetic tests before an accept signal is given. If the bill fails to pass these tests the acceptor drive system is reversed and the bogus bill or the like isdriven back out of thedevice.

A number of schemes have been devised by dishonest persons in attempting to cheat the acceptor described above. For example, pieces of paper or the like simulating dollar bills have been used in attempts to cheat the mechanism. Moreover, attempts have been madeto withdraw a genuine bill from the mechanism after it has passed the required tests as by attaching a string to the end of the bill. The acceptor shownin the prior art cannot usually be cheated by use of either of these expedients. First, the magnetic test provided is sufficiently sensitive that most facsimiles of genuine bills fail the test. Moreover, this acceptor willnot give credit in response to an extremely longstrip of paper. It is provided with a mechanical gate at the end thereof which is intended to prevent withdrawal of a genuine dollar bill after it has passed all the tests provided.

While the acceptor of the type shown in the Hooker patent operates satisfactorily in most instances in which attempts are made to cheat the device, dishonest persons have come up with increasingly ingenious schemes for cheating the system. First, the mechanical gate provided at the outlet of the acceptor described above is not as effective as is desirable. Secondly, some schemes have been devised for effectively passing the magnetic check provided in that system without the loss of the means which permits the test to be passed. Thus, even as sophisticated a system as is shown in the Hooker patent may, under some conditions, be cheated.

I have invented a post validator for a bill acceptor which overcomes defects of bill acceptors of the type known in the prior art. My post validator is compatible with existing bill acceptors. It incorporates an improved mechanical gate which prevents withdrawal of any material which has traveled beyond the gate. My post validator prevents cheating of the system even by an arrangement which passes the magnetic test of the acceptors known in the prior art.

SUMMARY OF THE INVENTION One object of my invention is to provide a post validator for a bill acceptor which overcomes the defects of bill acceptors of the type known in the prior art.

Another object of my invention isto provide a post validator which is compatible with existing bill acceptors of the prior art.

Another object of my invention is to provide a post validator for a bill acceptor which prevents cheating even by an arrangement which passes the magnetic test provided in a bill acceptor of the prior art.

Still another object of my invention is to provide a post validator for a bill acceptor which validator incorporates an improved oneway mechanical gate.

Other andfurther objects of 'my invention will appear from the following description.

In general my invention contemplates the provision of a post validator for a bill acceptor providing a preliminary magnetic check and a. photoelectric check of an item of currency in which the item is required to pass asecondary magnetic check at a location beyond an improved one-way mechanical gate positioned at the outlet of the bill acceptorbefore an accept signal willbe given.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings which form part of the instant specification and which are to be read in. conjunctiontherewith and in which like reference numetals are used to indicate like parts in the various views:

FIG. 1 is a sectional partial schematic view of a bill acceptor provided with my post validator.

FIG. 2 is an end elevation of the arrangement shown in FIG. 1 incorporating mypost validator.

FIG. 3 is a simplified diagram illustrating the logic of the electrical system incorporated in the post validator.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings the system shown therein includes a bill acceptor indicated generally by the reference character 10 of the general type shown and described in the Hooker patent referred to hereinabove. This acceptor 10 includes a housing 12 carryinga lower bill track 14 and an upper bill track- 16 makingup a channel or passage 18 into which a dollar bill can be inserted through a mouth 20. I dispose respective groups of rollers 22 and24 carried by shafts 26 and 28 at a first location along the length of passage 18 at which the leading edge of a bill can be inserted into the nip of the two rollers 22 and 24. As the bill moves along the passage its leading edge is pickedupin the nip between the groups of rollers 34 and 36 carried respectively by shafts 38 and 40. The bill moves further alongthe passage to the nip between groups of rollers 42 and 44 carried respectively by shafts 46 and 48. From the rollers 42 and 44 the bill travels along a downwardly inclined portion of the passage 18 to the nip between groups of rollers 50 and 52 carried by shafts 54 and 56 at the outlet of the bill acceptor 10.

As is more fully. described in the Hooker patent, the acceptor 10 includes a motor 58 which is energized to drive a shaft 60 which, through a gear box 62 drives an output shaft 64. As I have indicated. schematically by the dot-dash line 66 a timing belt driven by shaft 64 drives shafts 28, 40 and 48 at a predetermined speed. A rubber belt or the like indicated schematically by the dot-dash line, 68 drives shaft 54 from shaft 48.

As a bill is inserted portrait side up into passage 18 through the mouth 20 it first covers an aperture A1 in the lower track 14 to block light from a source L1 to a photocell P1. Upon traveling further along passage 18 the bill moves through the field of a permanent magnet M to cause the areas of magnetic ink thereon to magnetized. As is known in the art, these areas are located in the background region of the portrait. Next, the bill moves past the rollers 34 and 36 and under a magnetic head PM with which it is urged into contact by a pressure roller carried by a lever 72 supported on a pivot pin 74. A spring 76 normally urges lever 72 to a position at which the pressure roller 70 pushes the bill upwardly toward the head H1. A solenoid S is adapted to be energized in a manner to be describedto move roller 70 away from the bill path against the action of spring 76.

As it travels down the inclined portion of passage 18 finally the bill covers an aperture A4 to prevent light of a lamp L4 from reaching a photocell P4. Finally the bill moves to a position between the nip of roller 50 and 52 and is discharged from the bill acceptor 10.

The structure thus far described is similar to that shown in the Hooker patent referred to hereinabove. I modify the structure of the Hooker device by mounting the hub 78 of a claw 80 having teeth 82 on shaft 56. A spring 84 biases the claw 80 for movement into the path of a bill to be described hereinbelow. I also frictionally mount the hub 86 of a lower claw having teeth 90 on shaft 54. As will be described more fully hereinafter when shaft 54 is driven in a forward direction claw 88 moves out of the bill path to the dotdash line position shown in FIG. 1.

My post validator indicated generally by the reference character 92 includes a frame 94 having bushings 96 on which I mount a shaft 98 carrying outer drums 100 and 102 adjacent the ends thereof. I provide respective belts 104 and 106 associated with the drums 100 and 102 for holding a bill against the surface of the drums 100 and 102. The respective belts are trained around upper idler rolls 108 and 110, first lower idler rolls 112 and 114 and second idler rolls 116, one of which is shown in FIG. 1. Respective shafts 118, and 122 support the pairs of idler rolls 108 and 110, 112 and 114 and 116. A sprocket wheel 124 driven by a timing belt 126 which engages a sprocket wheel 128 on shaft 64 drives shaft 98 in the forward direction through a one-way clutch 127 to drive drums 100 and 102 and belts 104 and 106. This prevents the bill from being driven back toward the jaws.

I mount an idler drum 130 on the central portion of shaft 98 for free rotation relative thereto. A pivot pin 132 on the frame 94 supports a bracket 134 normally urged by a spring 136 to aposition at which a secondary magnetic sensing head H2 is urged toward the periphery of drum 130. In this way the drum does not rotate against the magnetic head to wear the same when no bill is in the system.

A vane 138 carried by hub 78 for rotation therewith is normally positioned between a photocell P6 and a Lamp L6.

As a bill is inserted into the channel 18 through the mouth 20 it first interrupts the light going from L1 to P1 to cause the photocell output to drop. This signal is amplified by an amplifier G1 and passes through an isolating diode 140 to an inverter 142. The inverter signal passes through a diode 144 to charge a capacitor 146 to apply the signal to an emitter follower 148. Capacitor 146 is so selected as to maintain an input signal to the emitter follower for a sufficient period of time after P1 is again illuminated to enable the acceptor to function. The output of the emitter follower is applied to respective amplifier channels 150 and 152, the outputs of which provide one input each to respective two-input-AND circuits 154 and 156 which lead to the forward and to the reverse relays (not shown) for the motor 58.

The output of inverter 142 also passes through two diodes 143 and 145 to an amplifier 147 which activates solenoid S until the trailing edge of the bill leaves the space between L1 and P1. When that occurs solenoid S deenergizes and pressure roller 70 forces the bill into intimate contact with head H1.

The output of inverter 142 also provides one input for two-input-AND circuit 158 which, as will be explained hereinafter, has no input applied to an inhibiting input terminal 160 so long as P1 and P4 are not blocked at the same time. I apply the output of the AND circuit 158 to the forward input terminal of a motor control flip flop 162 to provide the other input for circuit 154 to cause motor 58 to be energized to drive in the forward direction. Under the conditions just described, the motor 58 is energized to cause the bill to be moved along the channel 18. As the magnetic ink of the bill passes under magnet M it is magnetized temporarily. When that portion of the bill passes under the head H1, two spaced pulses X1 and X2 are produced on a channel 164 leading to an inhibiting input terminal 166 of a two-input-AND circuit 168. I have schematically indicated these pulses X1 and X2 adjacent to channel 164 in FIG. 3. It will .be appreciated that the existence of either of these two pulses at terminal 176 prevents circuit 158 from producing an output even in the presence of a signal at its other input terminal.

As the bill travels along the passage 18 its leading edge covers aperture A4 to block light from L4. As a result the output of P4 drops. This signal is amplified by an amplifier G4 and coupled by an isolating diode 170 to an inverter 172 the output of which is applied to a two-input-AND circuit 174 the other input of which is provided by invertor 142. The system is so arranged that the motor 58 is reversed if both P1 and P4 are covered at the same time, this condition indicating that an opaque piece of material longer than the length of a genuine bill has been inserted in the acceptor. I so arrange Al and A4 that the space therebetween is slightly greater than the length of a genuine dollar bill. I achieve this result by applying the output of circuit 174 to terminal 160 to inhibit circuit 158 to prevent the signal from inverter 142 from being applied to the forward drive section of flip flop 162. At the same time, a two-input-OR circuit 176 applies the output of AND circuit 174 to the reversing input terminal of flip flop 162 to provide a second signal for AND circuit 156 to reverse the motor. This signal may also be applied to solenoid S through a diode 177 and diode 145 to amplifier 147 to withdraw pressure roller 70.

The system is further arranged so that a genuine bill blocks aperture A4 at the time the first pulse X1 is being produced at head H1. As the aperture A4 is blocked, a capacitor C1 discharges through a resistor 178 to provide an input to an inverter 180 which provides a second pulse input X1 to the AND circuit 168. It will be seen that if the inhibiting input X1 to terminal 166 does not coincide with the X1 input to circuit 168 that circuit applies a signal to OR circuit 176 which is passed to the flip flop 162 again to reverse the motor 58. It will be apparent that the spacing between H1 and P4 is arranged to be equal to the distance between the leading edge of a genuine bill and the bill area which produces X1.

Upon further movement of the bill down the passage 18 it moves between rollers 50 and 52 and vane 138 moves to a position out of the space between L6 and P6 to cause P6 to produce an output which is amplified by an amplifier G6 and applied to an inverter 182 to cause the inverter output to drop to zero. When that occurs, a capacitor C2 discharges to cause inverter 180 to produce a pulse X2 which should coincide with pulse X2 if the bill is genuine. If not, the pulse causes circuit 168 to produce an output to reverse the motor. The distance between H1 and the nip between rollers 50 and 52 is equal to the distance between the leading edge of a genuine bill and the bill area which produces the pulse X2.

As the bill moves out of the passage 18 down through the space between claws 80 and 88 it enters into the nip between belts 104 and 106 and drums 100 and 102 so as to be carried into engagement with free wheeling drum 130. The drum. now rotates and the magnetic area of the bill is scanned by head H2 to produce an output on a channel 184. I apply the signal on channel 184 and the output of inverter 182 to a.twoinput-AND circuit 186 which is adapted to produce an accept or credit signal in response to the concomitant presence of signals at both of its input terminals. in the case of a genuine bill, claw 80 is released to permit vane 138 again to interrupt the light from source L6 at the same time as H2 produces a signal on channel 184'to cause circuit 186 to provide the accept signal. It will be appreciated that the distance between the point at which the trailing edge of a genuine bill releases claw 80 to permit it to be restored and the head H2 is equal to the distance between the trailing edge of the bill and the magnetized area which causes H2 to produce an output.

Finally, if the bill has successfully passed all tests, it is carried by belts 104 and 106 to a position at which it can drop into the cash box. If the bill fails the second magnetic check, or if vane 138 has not been restored by the time the second check is made, no accept signal is given, the device continues to run to the end of its cycle and nothing to which a string or long piece of material is attached can be withdrawn from the system.

It will be seen that l have accomplished the objects of my invention. I have invented a post validator for a bill acceptor which overcomes a defect of a bill acceptor known in the prior art. My post validator prevents generation of an acceptance signal even in the event that the checks provided by the acceptor have been dishonestly passed. My post validator requires that a secondary magnetic check be passed after a bill leaving the acceptor passes an improved one-way gate.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Having thus described my invention, what 1 claim is:

l. A bill acceptor and post validator system for delivering acceptable bills to a receptacle including in combination, means forming a passage having an inlet and an outlet, means located between said inlet and said outlet for producing a signal in response to a genuine bill travelling along said passage, a one way mechanical gate between said outlet and said recepta cle and means between said gate and said outlet for testing the genuineness of said bill.

2. A system as in claim 1 including an output line and means responsive to said testing means for passing said signal to said line.

3. A system as in claim 1 in which said testing means comprises a magnetic reading head and means for conveying said bill past said head.

4. A system as in claim 3 in which said testing means comprises an idler roll, means mounting said head for movement toward and away from said roll, and means for biasing said head toward said idler roll to provide a nip therebetween, said conveying means carrying said bill into said nip.

5. A system as in claim 1 in which said gate comprises a jaw, means mounting said jaw for movement adjacent said outlet, and means biasing said jaw into the path of a bill emerging from said outlet.

6. A post validator as in claiml including a shaft adapted to be driven in a forward direction and in a reverse direction, said gate including a jaw frictionally carried by said shaft for movement out of the path of a bill passing through said outlet in response to forward movement of said shaft and into said path in response to reverse movement of said shaft.

7. A system as in claim 1 in which said one way gate includes a jaw, means mounting said gate for movement adjacent said outlet, and means for biasing said jaw into the path of a bill moving through said outlet, said validator including a vane carried by said jaw for movement therewith, and means: associated with said vane for producing a signal in response to movement of said jaw back into said path as the trailing edge of a bill passes said jaw.

8. A system as in claim 7 in which said testing means comprises means for producing a second signal in response to passage of a genuine bill thereby and means responsive to the concomitant presence of both of said signals for producing a bill accept signal.

9. A system as in claim 1 in which said one way gate comprises an upper jaw having teeth, means mounting said jaw for movement adjacent said outlet, means biasteeth meshing in response to reverse movement of said shaft.

10. A post validator for a bill acceptor which tests the genuineness of a bill passing therethrough from an inlet to an outlet toward a receptacle located beyond said outlet including in combination, a one-way mechanical gate comprising a jaw mounted for movement adjacent said outlet and means for biasing said jaw into the path of a bill passing through said outlet, means responsive to return movement of said jaw into said path following movement of the trailing edge of a bill thereby for producing a first signal, a magnetic sensor located between said outlet and said receptacle for producing a second signal in response to the passage of a genuine bill thereby, means for conveying a bill from said outlet past said magnetic sensor, and means responsive to the concomitant presence of said first and second signals for producing a bill accept signal.

11. A post validator as in claim 10 in which said first signal producing means comprises a light source and a photocell mounted in spaced relationship and a vane carried by said jaw for movement into and out of the space between said source and said photocell.

12. A post validator as in claim 10 including an idler roller associated with said head and means biasing said head toward said idler roll.

13. A post validator as in claim 10 in which said jaw is a first jaw having teeth, said validator including a shaft mounted adjacent said outlet for movement in a forward direction and in a reverse direction and a second jaw carried by said shaft for movement out of the path of a bill passing through said outlet in response to forward movement of said shaft and for movement into the path in response to reverse movement of said shaft.

14. A bill acceptor and post validator system for producing a bill accept signal in response to passage of a genuine bill from an acceptor inlet to an acceptor outlet and through the validator to a receptacle wherein said bill carries a magnetized area, including in combination, a bill acceptor comprising an inlet, an outlet, means including a reversible drive for carrying a bill along a path between said inlet and said outlet, means responsive to insertion of a bill into said inlet for energizing said drive means in a forward direction,

photoelectric means along said path for producing a first electrical signal in response to passage of the leading edge of a bill thereby, means for producing a second signal in response to the passage of said magnetized area of a genuine bill thereby, means responsive to the presence of one of said signals for reversing said drive means, and means responsive to the concomitant presence of said first and second signals for inhibiting said reversing means, and a post validator comprising a one way mechanical gate adjacent said outlet, means responsive to passage of the trailing edge of a bill past said gate for producing a third signal, auxiliary means located between said outlet and said receptacle for magnetically producing a fourth signal in response to the passagethereby of said magnetized area of a genuine bill, means for conveying a bill from said outlet past said auxiliary means and means responsive to the concomitant presence of the third and fourth signals for producing said bill accept signah 15. A system as in claim 14 in which sai auxiliary means comprises an idler roller, a magnetic head, means mounting said head for movement toward and away from said roller and means biasing said head into engagement with said roller.

16. A system as in claim 15 in which said one way gate comprises an upper jaw having teeth, means mounting said upper jaw adjacent said outlet for movement into and out of the path of a bill, means biasing said upper jaw into said path, a shaft mounted adjacent to said outlet, means responsive to said drive means for driving said shaft, a lower jaw having teeth adapted to mesh with the upper jaw teeth, said lower jaw being frictionally carried by said shaft for movement out of said path in response to forward movement of said shaft and for movement into said path in response to reverse movement of said shaft.

17. A system as in claim 14 in which said conveying means is adapted to be driven in a forward direction to convey said bill from said outlet past said auxiliary means, and in which said conveying means comprises means for engaging said bill, a drive motor and a oneway clutch between said motor and said engaging means for driving said engaging means in said forward direction. 

1. A bill acceptor and post validator system for delivering acceptable bills to a receptacle including in combination, means forming a passage having an inlet and an outlet, means located between said inlet and said outlet for producing a signal in response to a genuine bill travelling along said passage, a one way mechanical gate between said outlet and said receptacle and means between said gate and said outlet for testing the genuineness of said bill.
 1. A bill acceptor and post validator system for delivering acceptable bills to a receptacle including in combination, means forming a passage having an inlet and an outlet, means located between said inlet and said outlet for producing a signal in response to a genuine bill travelling along said passage, a one way mechanical gate between said outlet and said receptacle and means between said gate and said outlet for testing the genuineness of said bill.
 2. A system as in claim 1 including an output line and means responsive to said testing means for passing said signal to said line.
 3. A system as in claim 1 in which said testing means comprises a magnetic reading head and means for conveying said bill past said head.
 4. A system as in claim 3 in which said testing means comprises an idler roll, means mounting said head for movement toward and away from said roll, and means for biasing said head toward said idler roll to provide a nip therebetween, said conveying means carrying said bill into said nip.
 5. A system as in claim 1 in which said gate comprises a jaw, means mounting said jaw for movement adjacent said outlet, and means biasing said jaw into the path of a bill emerging from said outlet.
 6. A post validator as in claim 1 including a shaft adapted to be driven in a forward direction and in a reverse direction, said gate including a jaw frictionally carried by said shaft for movement out of the path of a bill passing through said outlet in response to forward movement of said shaft and into said path in response to reverse movement of said shaft.
 7. A system as in claim 1 in which said one way gate includes a jaw, means mounting said gate for movement adjacent said outlet, and means for biasing said jaw into the path of a bill moving through said outlet, said validator including a vane carried by said jaw for movement therewith, and means associated with said vane for producing a signal in response to movement of said jaw back into said path as the trailing edge of a bill passes said jaw.
 8. A system as in claim 7 in which said testing means comprises means for producing a second signal in response to passage of a genuine bill thereby and means responsive to the concomitant presence of both of said signals for producing a bill accept signal.
 9. A system as in claim 1 in which said one way gate comprises an upper jaw having teeth, means mounting said jaw for movement adjacent said outlet, means biasing said upper jaw into the path of a bill passing through said outlet, a shaft adjacent said outlet adapted to be driven in a forward direction, a lower jaw frictionally carried by said shaft for movement out of said path in response to forward movement of said shaft and for movement into said path with the upper and lower jaw teeth meshing in response to reverse movement of said shaft.
 10. A post validator for a bill acceptor which tests the genuineness of a bill passing therethrough from an inlet to an outlet toward a receptacle located beyond said outlet including in combination, a one-way mechanical gate comprising a jaw mounted for movement adjacent said outlet and means for biasing said jaw into the path of a bill passing through said outlet, means responsive to return movement of said jaw into said path following movement of the trailing edge of a bill thereby for producing a first signal, a magnetic sensor located between said outlet and said receptacle for producing a second signal in response to the passage of a genuine bill thereby, means for conveying a bill from said outlet past said magnetic sensor, and means responsive to the concomitant presence of said first and second signals for producing a bill accept signal.
 11. A post validator as in claim 10 in which said first signal producing means comprises a light source and a photocell mounted in spaced relationship and a vane carried by said jaw for movement into and out of the space between said source and said photocell.
 12. A post validator as in claim 10 including an idler roller associated with said head and means biasing said head toward said idler roll.
 13. A post validator as in claim 10 in which said jaw is a first jaw having teeth, said validator including a shaft mounted adjacent said outlet for movement in a forward direction and in a reverse direction and a second jaw carried by said shaft for movement out of the path of a bill passing through said outlet in response to forward movement of said shaft and for movement into the path in response to reverse movement of said shaft.
 14. A bill acceptor and post validator system for producing a bill accept signal in response to passage of a genuine bill from an acceptor inlet to an acceptor outlet and through the validator to a receptacle wherein said bill carries a magnetized area, including in combination, a bill acceptor comprising an inlet, an outlet, means including a reversible drive for carrying a bill along a path between said inlet and said outlet, means responsive to insertion of a bill into said inlet for energizing said drive means in a forward direction, photoelectric means along said path for producing a first electrical signal in response to passage of the leading edge of a bill thereby, means for producing a second signal in response to the passage of said magnetized area of a genuine bill thereby, means responsive to the presence of one of said signals for reversing said drive means, and means responsive to the concomitant presence of said first and second signals for inhibiting said reversing means, and a post validator comprising a one way mechanical gate adjacent said outlet, means responsive to passage of the trailing edge of a bill past said gate for producing a third signal, auxiliary means located between said outlet anD said receptacle for magnetically producing a fourth signal in response to the passage thereby of said magnetized area of a genuine bill, means for conveying a bill from said outlet past said auxiliary means and means responsive to the concomitant presence of the third and fourth signals for producing said bill accept signal.
 15. A system as in claim 14 in which said auxiliary means comprises an idler roller, a magnetic head, means mounting said head for movement toward and away from said roller and means biasing said head into engagement with said roller.
 16. A system as in claim 15 in which said one way gate comprises an upper jaw having teeth, means mounting said upper jaw adjacent said outlet for movement into and out of the path of a bill, means biasing said upper jaw into said path, a shaft mounted adjacent to said outlet, means responsive to said drive means for driving said shaft, a lower jaw having teeth adapted to mesh with the upper jaw teeth, said lower jaw being frictionally carried by said shaft for movement out of said path in response to forward movement of said shaft and for movement into said path in response to reverse movement of said shaft. 